Drosophila larvae synthesize the putative oncometabolite L-2-hydroxyglutarate during normal developmental growth

Abstract

L-2-hydroxyglutarate (L-2HG) has emerged as a putative oncometabolite that is capable of inhibiting enzymes involved in metabolism, chromatin modification, and cell differentiation. However, despite the ability of L-2HG to interfere with a broad range of cellular processes, this molecule is often characterized as a metabolic waste product. Here, we demonstrate that Drosophila larvae use the metabolic conditions established by aerobic glycolysis to both synthesize and accumulate high concentrations of L-2HG during normal developmental growth. A majority of the larval L-2HG pool is derived from glucose and dependent on the Drosophila estrogen-related receptor (dERR), which promotes L-2HG synthesis by up-regulating expression of the Drosophila homolog of lactate dehydrogenase (dLdh). We also show that dLDH is both necessary and sufficient for directly synthesizing L-2HG and the Drosophila homolog of L-2-hydroxyglutarate dehydrogenase (dL2HGDH), which encodes the enzyme that breaks down L-2HG, is required for stage-specific degradation of the L-2HG pool. In addition, dLDH also indirectly promotes L-2HG accumulation via synthesis of lactate, which activates a metabolic feedforward mechanism that inhibits dL2HGDH activity and stabilizes L-2HG levels. Finally, we use a genetic approach to demonstrate that dLDH and L-2HG influence position effect variegation and DNA methylation, suggesting that this compound serves to coordinate glycolytic flux with epigenetic modifications. Overall, our studies demonstrate that growing animal tissues synthesize L-2HG in a controlled manner, reveal a mechanism that coordinates glucose catabolism with L-2HG synthesis, and establish the fly as a unique model system for studying the endogenous functions of L-2HG during cell growth and proliferation.ne of the hallmarks of cancer is a dramatic reprograming of cellular metabolism that results in enhanced biosynthesis (1). These metabolic changes are particularly apparent in tumors that use the Warburg effect, also referred to as aerobic glycolysis, a metabolic program characterized by elevated levels of glucose consumption and enhanced lactate production (1, 2). By activating aerobic glycolysis, tumors are able to synthesize macromolecules rapidly from glycolytic intermediates. In addition, elevated levels of lactate dehydrogenase (LDH) activity allow proliferating cells to synthesize lactate and maintain the NAD + levels required for high rates of glucose catabolism and biomass production (1).The metabolic reprogramming of cancer cells, however, extends beyond biosynthesis, as many tumors also generate progrowth metabolites, or oncometabolites, that promote tumor formation via nonmetabolic means. Most notable among these compounds is D-2-hydroxyglutarate (D-2HG), which is associated with cancers such as gliomas and acute myelogenous leukemias (3). Although D-2HG is generated as a normal byproduct of γ-hydroxybutyrate metabolism (4), oncogenic D-2HG production is the result of neomorphic mutations in the active site of isocitrate dehydrogenas...

Alternative oxidase confers nutritional limitation on Drosophila development

“…It is highly expressed in larvae and is also induced by steroid signaling (Abu-Shumays & Fristrom, 1997). LDH activity declines during metamorphosis (Rechsteiner, 1970), reflecting the drop in its messenger RNA late in larval development (Graveley et al, 2011), with the accumulated lactate being mostly used up during the prepupal stage (Li et al, 2017). In larvae, glycolysis serves the needs of adenosine triphosphate (ATP) production and supplies carbon skeletons for biosynthesis via the TCA cycle (Tennessen, Baker, Lam, Evans, & Thummel, 2011), while in the pupa, triglycerides are catabolized mainly in mitochondria.…”

Genetic variation for ontogenetic shifts in metabolism underlies physiological homeostasis inDrosophila

“…dLDH activity recycles NAD + which allows 471 for continued glycolytic ATP production and supports the TCA cycle in generating cellular 472 building blocks. Furthermore, dLDH expression and lactate production results in the 473 accumulation of the metabolic signaling molecule L-2-hydroxyglutarate that affects genome-474 wide DNA methylation and promotes cellular proliferation (Li et al, 2017). We found that 475 second-instar lactate accumulation was strongly affected by genotype, suggesting differential 476 timing of this switch among both wild-type and mito-nuclear genotypes.…”

“…Using glycolytic ATP production may seem counterintuitive and less efficient than oxidative 457 ATP production. However, glycolytic ATP production may provide several developmental dERR is responsible for a vital transcriptional switch of carbohydrate metabolism in second-469 instar larvae ) that coincides with increases in lactate dehydrogenase 470 (dLDH) and lactate accumulation (Li et al, 2017). dLDH activity recycles NAD + which allows 471 for continued glycolytic ATP production and supports the TCA cycle in generating cellular 472 building blocks.…”

Methods for studying the metabolic basis of Drosophila development

“…The protocol and the principles underlying the calculation of metabolic flux ratios were well summarized previously . Metabolic flux analysis is gaining traction in Drosophila studies and has made important contributions to our understanding of fat synthesis, diet‐induced obesity, and glucose oxidation …”